Even though its not highly exciting, you really need to play in multiple new player games to get a good feel for the game. One inexperienced player very often makes the difference between winning and losing - that's why you often get the cold shoulder from folks in lobbies if you join a game for mids and >. Anyway, here's what actually happens in practice. You start hosting or joining new player games. You get more experience. You start to get to know folks. Eventually they get to know how you play and what to expect (eg this guy buys the things we need for the citadel, this guy feeds, etc). After doing that for a bit, you eventually start seeing the same people over and over and you eventually are welcomed into more and more games. For instance, if you and I were pals and I feel confident you are a solid player, then you'd be able to get into a more experienced game - even if your stats were bad because I'd tell everyone you are a solid player.
Anyway, that's just how it goes. I'd recommend playing some against the AI to get familiar with all the mechanics and Demigods. Then I'd start hosting new player games. Hopefully before too long you build up a rhythm and find yourself getting welcomed into more and more games.
re: the attitude toward new players by folks that have been in the community a long time - well, you are generally correct here. Some folks are certainly kind and helpful to new players. Others can be complete crap heads. I'd just make sure you stick to joining either all welcome or new player games for a bit. You put the time in, you'll get better and those same folks that wanted to kick you from their team will be lucky to have you as a teammate.